Password Protect A Page with Single Password

I really like all of your workaround to the main request, but as @gtc I need to input username or password only. The plugin shared by @aoimedia is exactly what I need so, someone has a V2 compatible version of this plugin?
Thank you!

As far as I know, there is no v2 compatible version of the plugin. But I don’t think it is necessary, because the solution suggested by @bastianallgeier (hardcoding the user name) has the same effect as the plugin (with less work).

I just implemented the here described method to protect a β€œpress” area from public access. Now I wonder if this approach is also save against brood-force or password-spam attacks from internal kirby mechanics or do I have to take care of that myself?

No, you need to do the brute-force protection yourself. The Panel has a protection, but it is not applied to frontend logins with $user->login() at the moment.